Lactotransferrin receptors

Iron transport. Experiments in vitro carried out in 1979 by Cox et al. [164] and using human intestinal biopsies demonstrated that human lactotransferrin can donate iron to intestinal mucosal cells. The characterization of a specific intestinal lactotransferrin receptor in rabbit [48], mouse [165,166], Rhesus monkey [167] and human foetal intestinal brush border membranes [168] reinforces the concept of the role of lactotransferrin in intestinal iron absorption. However, despite these findings, the nutritional activity of lactotransferrin is still a subject of controversy (for a review, see ref. [7]). 

Lactotransferrins also possess a bactericidal effect observed in 1977 by Arnold et al. [176] according to Tomita et al. [177,178] this is due to the liberation of short peptides like lactoferricin B (fragment 17-41 of bovine lactotransferrin) by partial proteolysis. Lactoferricin B derived from the peptidic segment binding to lactotransferrin receptors. The industrial interest in lactoferricin is evident. 

Lactotransferrin receptors. The existence of a lactotransferrin receptor was first demonstrated by Van Snick and Masson in 1976 [191] at the surface of mouse peritoneal macrophages and lymphocytes. Since this discovery, the presence of lactotransferrin receptors has been demonstrated at the surface of various cells (for reviews, see refs. [156,158,192,193]) rabbit [48], mouse [165,166], monkey [167] and human [168] enterocytes human HT29 and Caco-2 enterocyte cell lines [194] human monocytes (reviewed in ref. [195]), human alveolar macrophages [196], human neutrophils [195,197], human resting lymphocytes [197], human activated lymphocytes [189], human Jurkat T cell line [190], human epithelial mammary cell line [198], human platelets [199,200] and megakaryocytes [201], hepatocytes [202,203] and in bacteria (for a review see refs. [204,205]). 

Contrary to serotransferrin receptors, little is known about the structure, physicochemical properties and gene expression of lactotransferrin receptors. Their main characteristics, which are totally different from those of serotransferrin receptors, can be summarized as follows ... 

Spik, G., Legrand, D., Leveugle, B., Mazurier, J., Mikogami, T., Montreuil, J., Pierce, A., and Rochard, E. 1994b. Characterization of two kinds of lactotransferrin (lactoferrin) receptors on different target cells. Adv. Exp. Med. Biol. 357, 13-19. 

These findings caught the attention of many milk companies since, rightly or wrongly, a nutritional role was suggested for these proteins in iron transport for the mammalian newborn. The discovery of lactotransferrin specific receptors in the brush-border of enterocytes [48] supports this concept. In addition, as suggested by Montreuil et al. [34], human lactotransferrin could intervene in the intestinal defence of breast-fed infants by a... 

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